Tactical vertical takeoff and landing (VTOL) aircraft are known. Such known tactical VTOL aircraft are generally quick and maneuverable rotary blade aircraft, i.e. helicopters, that are used for airborne special operations. Being small and relatively quiet, and having a sufficient load to size ratio, these VTOL aircraft have provided a stable platform for the special operations world. They are sufficiently suited for providing a ‘ride to target’ and air support for ground troops. Technical evolution of such known VTOL aircraft has resulted in VTOL aircraft that can be used for ‘fast-rope’ insertions and/or be outfitted with weapons such as mini .50 caliber machine guns, missiles, grenade launchers and aerial rockets. However, known tactical VTOL aircraft are still range/payload constrained and need to be flown with hostile ground fire, ever maturing radar, infrared and acoustic based threats in mind.
A variety of methods have been employed to provide vertical takeoff capability. These methods include providing ducts to redirect the discharge from a main propulsion unit, providing a tilt mechanism to permit main engine(s) to tilt, and providing separate engines for driving fan systems to lift the aircraft. Aircraft range and payload capabilities are reduced when weight and structural changes required to incorporate vertical takeoff capabilities are incorporated into an aircraft. For example, oversized axial propulsion will reduce cruise efficiency. The complexity of an aircraft designed to accommodate both horizontal and VTOL capabilities also increases the maintenance requirements on the aircraft and therefore increases the overall life cycle costs to operate the aircraft.
Additionally, known VTOL aircraft must still be operated in view of increasingly dangerous risks. For example, detection/observation methods such as radar, infrared, acoustical, electromagnetic, contrails and visual detection pose serious survivability threats to known VTOL aircraft. Acoustically, the rotors of typical VTOL aircraft generate a strong, broadband signature that is very distinctive making them very vulnerable to acoustical detection. Untreated engine exhaust create an easy target for shoulder launched heat seeking missiles and very little radar cross section detection is possible. The maturation of detection sensors and antiaircraft weapons has progressed to a point that aircrews and passengers are at an ever increasing risk.
A need therefore exists for a VTOL aircraft with the characteristics of affordability, enhanced range/payload, high speed, and low vulnerability to hostile detection and threats.